Lekko Node Server SDK

The Lekko Server SDK for Node.js

Getting Started

Installation

You can install @lekko/node-server-sdk using NPM or Yarn.

@lekko/node-server-sdk depends on source code generated by Buf which is hosted on their NPM registry. Prior to adding the Lekko SDK, configure your package manager to use Buf's NPM registry for @buf scoped packages.

Note

Due to the dependency on Buf's source code generation, we currently do not support installing with Yarn versions older than v2 (a.k.a. Yarn Classic). Please refer to Buf's docs here for more information.

NPM

The following command updates your .npmrc file.

npm config set @buf:registry https://buf.build/gen/npm/v1

Yarn

You must edit your .yarnrc.yml file to include the following scope:

npmScopes:
  buf:
    npmRegistryServer: https://buf.build/gen/npm/v1

Then, you can add the package to your project by running npm install @lekko/node-server-sdk or yarn add @lekko/node-server-sdk.

Usage

Initializing a cached Lekko client

Creates a client that fetches configs from Lekko backend and caches them in memory. Configs are kept up to date via polling.

const lekko = require("@lekko/node-server-sdk");

const client = await lekko.initCachedAPIClient({
    apiKey: <API_KEY>,
    repositoryOwner: <REPOSITORY_OWNER>,
    repositoryName: <REPOSITORY_NAME>,
});

const context = new lekko.ClientContext().setString("my_context_key", "my_context_value");
const stringConfig = await client.getString("my_namespace", "my_config", context);
console.log(stringConfig);

Initializing a cached Lekko client in git mode

Creates a client that reads configs from a git repository on disk and caches them in memory. Configs are kept up to date via a file watcher.

const lekko = require("@lekko/node-server-sdk");

const client = await lekko.initCachedGitClient({
    apiKey: <API_KEY>,
    repositoryOwner: <REPOSITORY_OWNER>,
    repositoryName: <REPOSITORY_NAME>,
    path: 'path/to/config/repo',
});

const context = new lekko.ClientContext().setString("my_context_key", "my_context_value");
const boolConfig = await client.getBool("default", "example", context);
console.log(boolConfig);

Note on using ES modules

In a traditional Node.js environment, you initialize the Lekko client using CommonJS modules:

const lekko = require("@lekko/node-server-sdk");

Modern versions of Node also support ES (ECMAScript) modules, using the import syntax:

import * as lekko from "@lekko/node-server-sdk"; // or
import { initAPIClient, initSidecarClient } from "@lekko/node-server-sdk";

The SDK is packaged as a CommonJS module. To use it as an ES module like the above example, add the following to your package.json:

{
  "type": "module"
}

To learn more about the Node.js module system, refer to their docs here.

Example

See: https://github.com/lekkodev/node-server-sdk/tree/main/example-ts